Publications Published in Journal of the American Water Resources Association

1. A comparison of delta change and downscaled GCM scenarios for three mountainous basins in the United States. Hay, L. E.; Wilby, R. J. L.; Leavesley, G. H..
   Journal of the American Water Resources Association: 2000
   Notes
   Simulated daily precipitation, temperature, and runoff time series were compared in three mountainous basins in the United States: (1) the Animas River basin in Colorado, (2) the East Fork of the Carson River basin in Nevada and California, and (3) the Cle Elum River basin in Washington State. Two methods of climate scenario generation were compared: delta change and statistical downscaling. The delta change method uses differences between simulated current and future climate conditions from the Hadley Centre for Climate Prediction and Research (HadCM2) General Circulation Model (GCM) added to observed time series of climate variables. A statistical downscaling (SDS) model was developed for each basin using station data and output from the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis regridded to the scale of HadCM2.
   
   
   
2. Climate change impacts uncertainty for water resources in the San Joaquin River Basin, California. Brekke, L. D.; Miller, N. L.; Bashford, K. E.; Quinn, N. W. T.; Dracup, J. A..
   Journal of the American Water Resources Association: 2004
   Notes
   A climate change impacts assessment for water resources in the San Joaquin River region of California is presented. Regional climate projections are based on a 1 percent per year CO2 increase relative to late 20th Century CO2 conditions. Two global projections of this CO2 increase scenario are considered (HadCM2 and PCM) during two future periods (2010 to 2039 and 2050 to 2079). HadCM2 projects faster warming than PCM. HadCM2 and PCM project wetter and drier conditions, respectively, relative to present climate. In the HadCM2 case, there would be increased reservoir inflows, increased storage limited by existing capacity, and increased releases for deliveries and river flows. In the PCM case, there would be decreased reservoir inflows, decreased storage and releases, and decreased deliveries. Impacts under either projection case cannot be regarded as more likely than the other. Most of the impacts uncertainty is attributable to the divergence in the precipitation projections. The range of assessed impacts is too broad to guide selection of mitigation projects. Regional planning agencies can respond by developing contingency strategies for these cases and applying the methodology herein to evaluate a broader set Of CO2 scenarios, land use projections, and operational assumptions. Improved agency access to climate projection information is necessary to support this effort.
   
   
   
3. Climate change sensitivity analysis for two California watersheds: Addendum to downscaled climate and streamflow study of the southwestern United States (vol 35, pg 1525, 1999). Miller, N. L.; Kim, J..
   Journal of the American Water Resources Association: 2000
   Notes
   In the December 1999 JAWRA Special Issue on Water Resources and Climate Change, Miller et al., presented an overview of downscaled climate and streamflow study of the southwestern United States. This manuscript included an initial sensitivity study of a doubled atmospheric carbon dioxide concentration on western U.S. precipitation and streamflow. In the published manuscript, Figure 12a shows the mean annual precipitation for 1981 to 1984 and Figure 15 shows the mean annual precipitation difference between the downscaled control simulation and the 2xCO(2) projection. Both Figure 12a and Figure 15 are in units of mm/month. These units are incorrect, the correct units are mm/year. An additional California watershed is included here, as is more analysis of the streamflow result due to climate change.
   
   
   
4. Ground Water/Surface Water Reponses to Global Climate Simulations, Santa Clara-Calleguas Basin, Ventura, California. Hanson, Randall T.; Dettinger, Michael D..
   Journal of the American Water Resources Association: 2005
   Notes
   Climate variations can play an important, if not always crucial, role in successful conjunctive management of ground water and surface water resources. This will require accurate accounting of the links between variations in climate, recharge, and withdrawal from the resource systems, accurate projection or predictions of the climate variations, and accurate simulation of the responses of the resource systems. To assess linkages and predictability of climate influences on conjunctive management, global climate model (GCM) simulated precipitation rates were used to estimate inflows and outflows from a regional ground water model (RGWM) of the coastal aquifers of the Santa ClaraCalleguas Basin at Ventura, California, for 1950 to 1993. Interannual to interdecadal time scales of the El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) climate variations are imparted to simulated precipitation variations in the Southern California area and are realistically imparted to the simulated ground water level variations through the climate-driven recharge (and discharge) variations. For example, the simulated average ground water level response at a key observation well in the basin to ENSO variations of tropical Pacific sea surface temperatures is 1.2 m/ºC, compared to 0.9 m/ºC in observations. This close agreement shows that the GCM-RGWM combination can translate global scale climate variations into realistic local ground water responses. Probability distributions of simulated ground water level excursions above a local water level threshold for potential seawater intrusion compare well to the corresponding distributions from observations and historical RGWM simulations, demonstrating the combination's potential usefulness for water management and planning. Thus the GCM-RGWM combination could be used for planning purposes and when the GCM forecast skills are adequate for near term predictions.
   
   
   
5. Potential impacts of climate change on California hydrology. Miller, N. L.; Bashford, K. E.; Strem, E..
   Journal of the American Water Resources Association: 2003
   Notes
   Previous reports based on climate change scenarios have suggested that California will be subjected to increased wintertime and decreased summertime streamflow. Due to the uncertainty of projections in future climate, a new range of potential climatological future temperature shifts and precipitation ratios is applied to the Sacramento Soil Moisture Accounting Model and Anderson Snow Model in order to determine hydrologic sensitivities. Two general circulation models (GCMs) were used in this analysis: one that is warm and wet (HadCM2 run 1) and one that is cool and dry (PCM run B06.06), relative to the GCM projections for California that were part of the Third Assessment Report of the Inter-governmental Panel on Climate Change. A set of specified incremental temperature shifts from 1.5
   
   
   
6. The impacts of climatic changes for water resources of the Colorado and Sacramento-San Joaquin River Basins. Gleick, P. H.; Chalecki, E. L..
   Journal of the American Water Resources Association: 1999
   Notes
   A wide variety of regional assessments of the water-related impacts of climatic change have been done over the past two decades, using different methods, approaches, climate models, and assumptions. As part of the Water Sector research for the National Assessment of the Implications of Climatic Variability and Change for the United States, several major summaries have been prepared, looking at the differences and similarities in results among regional research projects. Two such summaries are presented here, for the Colorado River Basin and the Sacramento River Basin. Both of these watersheds are vitally important to the social, economic, and ecological character of their regions; both are large snowmelt-driven basins; both have extensive and complex water management systems in place; and both have had numerous, independent studies done on them.